The assignment statement in C

  • The assignment statement in C has the same syntax and meaning as Java: 

       var = expression ;

      (1) Evaluate the expression on the RHS
      (2) Convert if necessary to the correct data type
      (3) Assign the result to the variable on the LHS

  • Warning:

      • C will always perform the conversion automatically for number data types

      • Even when the RHS value is a wider data type than the LHS variable !

An assignment statement example to hightlight the difference in C and Java

  • The following assignment statement will compile and run correctly in C: 

    #include <stdio.h>

int main( int argc, char* argv[] )
{
   double r = 1.0;
   int    integralAreaOfCircle;

   integralAreaOfCircle = 3.14 * r * r;  // Assign double value 
                                         // to an int typed variable

   printf("Integral area of circle with radius %f = %d\n",
                r, integralAreaOfCircle);
}

  • This assignment statement will cause compile error in Java...

    (Java requires a casting operator...)

DEMO: demo/C/set1/casting3.c

An assignment statement example to hightlight the difference in C and Java

  • The same assignment statement will cause compile error in Java: 

    public class casting3
{
   public static void main( String[] args )
   {
      double r = 1.0;
      int    integralAreaOfCircle;

      integralAreaOfCircle = 3.14 * r * r;  // Assign double value 
                                            // to an int typed variable

      System.out.printf("Integral area of circle with radius %f = %d\n",
                          r, integralAreaOfCircle);
   }
}

    (Java requires a casting operator...)

DEMO: demo/C/set1/casting3.java